Experimental Studies of the specific effects of luminal narrowing, heart rate, stroke, volume, peripheral resistance, arterial pressure and flow on individual dimensional and nondimensional variables of extremity and "simulated" carotid arterial velocity waveforms will be completed. Special angle orienting probes will be fabricated and tested. The optimum combination of nondimensional velocity waveform variables for the clinical diagnosis of carotid arterial occlusive disease will be determined and an automated velocity waveform analyzer will be developed using a dedicated microcomputer. The clinical value of femoral artery velocity waveform analysis in predicting the presence and severity of proximal or distal occlusive lesions will be explored.